Missing unit tests for download_text_from_url utility

[xiaoaoshan]

Hi,

I noticed that the function download_text_from_url does not seem to have dedicated unit tests.

Since this function involves network I/O and text extraction, it may benefit from:

• Mocked HTTP response testing
• Error handling validation (e.g., timeout, invalid URL)
• Encoding/decoding scenarios

Would you consider adding tests for this function?

If needed, I’d be happy to contribute a PR.

Thanks!